This Program Project will confinue our examinafion ofthe structure and funcfion of proteins required for alphavirus and flavivirus replication. These viruses consfitute important human pathogens and include members such as dengue and West Nile as well as potenfial bioterrorist weapons like Venezuelan equine encephalifis and fick-borne encephalifis virus. The experiments that are proposed require significant shared resources to accomplish the objectives that are listed in the Introducfion to this proposal. The Purdue Structural Biology Group has established some of these shared resources over many years. The resources include instrumentafion, service and support, and dedicated personnel for their operafion. The funds requested for these facilifies are required for their usage and maintenance on applicafions direcfiy related to the Program Project. These facilifies include X-ray, EM, macromolecular protein expression and purificafion, cell and virus culture, compufing and administrative components. The funcfions of each of these facilities are detailed in this Core Proposal. The facilities described in this Core are absolutely essenfial for the success of the individual ROI research proposals. RELEVANCE (See instructions): Structural studies of viruses require a substanfial investment in high-end instrumentafion such as high energy electron microscopes, intensive compufing power, large scale virus growth capabilities, and a dedicated staff of trained personnel. This core proposals seeks resources to maintain these essenfial capabilifies to carry out the structure and funcfional studies of these important human pathogen.